The invention relates to a process for the production of a material for sealing and/or healing wounds which comprises the even application of a liquid composition to a suitable carrier.
A material for sealing and healing wounds which comprises a collagen carrier, coated with a fibrinogen component, a thrombin component and possible additional components is known from U.S. Pat. No. 4,453,939.
To prepare a material of this kind, a fibrinogen component, a thrombin component and possible additives are suspended in an organic solvent, e.g. ethanol, and subsequently applied to a suitable carrier, e.g. by means of spraying.
In spraying such a suspension containing a fibrinogen component and a thrombin component on the carrier, several problems arise, because the suspension to be applied is difficult to handle. For example, the nozzles usually used for these purposes clog immediately. Air atomizing nozzles permit the use of a larger diameter, but even in this case, only nozzles with the largest diameter available allow working with a sufficient lack of trouble. However, these nozzles show a fatal disadvantage. The indistinct definition of the exiting stream does not result in an application of an even layer of the suspension, but creates a trapezoidal coating profile on the carrier. This leads to considerable losses of valuable and expensive suspension and of carrier material at the edges.
A device for applying a liquid film to a fabric web according to the pouring-out principle is known from EP-A 472 050. By means of individual partitions for liquid which are located directly next to one another, this device achieves a forced distribution of the liquid from a feed opening to a number of outflow openings. The liquid is distributed in the form of a family tree, i.e step by step from one opening to two, four, eight, sixteen, etc. outflow openings. Such a device is not suitable for an even distribution of a suspension containing fibrinogen and thrombin components, as the several divisions of the liquid stream cause conglutination and clogging of the partitions by the suspension. Furthermore, such a conglutination and clogging occurs to a greater extent than when nozzles are used.